On Tue, Dec 25, 2018 at 8:44 AM <[email protected]> wrote: > On Monday, December 24, 2018 at 9:35:05 PM UTC, Bruce wrote: >> >> On Tue, Dec 25, 2018 at 4:43 AM John Clark <[email protected]> wrote: >> >>> On Sun, Dec 23, 2018 at 5:38 PM Bruce Kellett <[email protected]> >>> wrote: >>> >>> *> Flatness is explained if the unknown parameter k in the FRW solution >>>> is set to zero. The the universe is always flat, no need to fine tune. >>>> Setting k = 1 or k = -1 is just as fine-tuned or not as k=0.* >>>> >>> >>> There are an infinite number of ways space could have been curved but >>> you picked one particular way (no curvature at all) for your initial >>> conditions and did so for no particular reason other than to make the >>> theory fit the facts that you already knew. Inflation explains why >>> spacetime curvature could have any finite value whatsoever when the >>> universe first came into existence and it would still look flat today even >>> with our most sensitive instruments. It didn't have to start out with >>> spacetime being zero or anything close to it, and that doesn't sound >>> fined-tuned to me. >>> >>> And the same thing is true of temperature, why are things at the same >>> temperature when there was no time for them to come into thermal >>> equilibrium? Inflation explains why, your explanation is they just did. >>> Inflation says that 10^-35 seconds after the start of the universe and it >>> had doubled in size about a hundred times (and 10^35 seconds is a long >>> long time compared to the Planck Time of 10^-43 seconds) the difference in >>> temperature in our part of the universe would be almost zero but not >>> precisely zero due to random quantum variations, and quantum theory allows >>> you to calculate the intensity and size of what those temperature >>> variations should have been. And you can also calculate what those >>> temperature variations would evolve into after the universe has been >>> expanding for 380,000 years, and what we calculate and what we see are the >>> same. >>> >>> That's also how we know that at the very largest scale the universe is >>> in general flat. They did this by looking at the oldest thing we can >>> see, the Cosmic Microwave Background Radiation (CMBR) formed just 380,000 >>> years after the Big Bang. So if we look at a map of that background >>> radiation the largest structure we could see on it would be 380,000 light >>> years across, spots larger than that wouldn't have had enough time to form >>> because nothing, not even gravity can move faster than light, a larger lump >>> wouldn't even have enough time to know it was a lump. >>> >>> So how large would an object 13.8 billion light years away appear to us >>> if it's size was 380,000 light years across? The answer is one degree of >>> arc, but ONLY if the universe is flat. If it's not flat and parallel lines >>> converge or diverge then the image of the largest structures we can see in >>> the CMBR could appear to be larger or smaller than one degree depending on >>> how the image was distorted, and that would depend on if the universe is >>> positively or negatively curved. But we see no distortion at all, in this >>> way the WMAP and Planck satellite proved that the universe is in general >>> flat, or at least isn't curved much, over a distance of 13.8 billion light >>> years if the universe curves at all it is less than one part in 100,000. >>> >>> >>>> >> It would seem to me that if two theories can explain observations >>>>> then the one with the simpler initial conditions is the superior. >>>>> >>>> >>>> *> The trouble is that inflation is not a simple theory. Where does >>>> the inflation potential come from?* >>>> >>> >>> From the same place gravitational potential does I suppose, but >>> inflation would be simpler, in General Relativity gravity needs a tensor >>> field but inflation only needs a scalar field. >>> >>> >>>> > *Why don't we see the inflaton?* >>>> >>> >>> Maybe we do see it, maybe the acceleration of the universe we see today >>> is the inflation field at work having undergone a phase change when the >>> universe was 10^-35 sec old and switched into a much lower gear. Or maybe >>> not. Andrei Linde thinks the inflation field decayes away like radioactive >>> half life, and after the decay the universe expanded at a much much more >>> leisurely pace. But for that idea to work Guth's the inflation field had to >>> expand faster than it decayed, Linde called it "Eternal Inflation". Linde >>> showed that for every volume in which the inflation field decays away 2 >>> other volumes don't decay. So one universe becomes 3, the field decays in >>> one universe but not in the other 2, then both of those two universes >>> splits in 3 again and the inflation field decays away in two of them but >>> doesn't decay in the other 4. And it goes on like this forever creating a >>> multiverse. >>> >>> If any of this is true we may be able to prove it because Eternal >>> Inflation would create gravitational waves with super long wavelengths that >>> would produce very slight changes in the polarization of the cosmic >>> microwave background radiation that we should be able to detect before >>> long, assuming they exist. >>> >> >> You seem to be convinced by inflation theory. I am a lot more sceptical >> because I see problems that you brush away contemptuously. Why has the >> inflation not been seen at LHC? If it decayed into ordinary matter, it must >> couple to ordinary matter, and so can be produced in high energy >> collisions. But no evidence for any such particle has been found. Inflation >> does not solve the horizon problem, either. At the end of the inflationary >> period, the temperature was absolute zero everywhere -- no fluctuations. >> The hot big bang came from the reheating phase where the inflation field >> decayed into ordinary matter. As a quantum process, this would have >> occurred randomly everywhere, so there would have been no uniformity in >> temperate at all. >> > > Do you have a typo at end? Did you intend to write "... so there would > have been no NON uniformity in temperature at all." AG >
I mistyped "temperature", but I meant NO UNIFORMITY. That is why inflation theory has some enormous holes -- we see an essentially uniform temperature, and inflation does not really give this without some exceptional fine tuning. Bruce -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
